Tardive dyskinesia is the syndrome of abnormal movements that arises from prolonged intake of neuroleptic medication. These abnormal movements can severely detract from performance in a wide range of motor skills, including vocational and self-help activities. A significant proportion of the abnormal movements associated with developmentally disabled individuals are reflections of tardive dyskinesia. It is not clear how these movement abnormalities differ from non-medication induced abnormal movements, such as institutionalized stereotypes of the developmentally disabled. The focus of this proposal is to continue to examine the motor control characteristics of the abnormal and stereotypic movement disorders of the developmentally disabled, and in particular, those abnormal movements associated with tardive dyskinesia. A formal movement analysis of the movement disorders of developmentally disabled subjects under neuroleptic medication and on addition and withdrawal from neuroleptic medication protocols will be conducted under a range of different postural and movement task conditions. This movement analysis will: (1) provide a description of the stereotypic movements that reflects organizational coordination and control properties of the central nervous system; (2) allow comparison to matched normal and other developmentally disabled groups that have not been on medical regimes; (3) allow an examination of the effects of neuroleptic medication on the motor control properties of movement disorders; (4) provide a formal test of the observer "rating scale" method currently used to characterize the abnormal movements of tardive dyskinesia; and (5) evaluate the posture and movement tests as a more sensitive screening device for tardive dyskinesia than the traditional techniques of clinical observation and motor performance rating scales.